Gravity Brake Bleed

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hypervish

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Hey, how's everyone's Saturday going?

I have a 96' Dodge Grand Caravan ES 3.8L and I want to bleed the brakes. These van's are notorious for [censored] brakes, failing transmissions (i'm on the 4th one), and other stupid stuff like electrical gremlins which make the wipers go on and off at random times.

I'm thinking about doing a gravity bleed. I don't think the brake fluid has ever been changed and the van now has 224k miles on it. It's mainly used as a part's hauler, or other work in which I don't want to get my DD dirty.

Any recommendations on what brake fluid to get?
Also, do I need a clear tube for the brake bleeder screw, If all I'm doing a gravity bleed? If so, what size clear tube?

Here's how I plan on doing it, please correct me If I'm wrong. (btw: I'm not draining the rear brakes).

1. Open brake fluid cap under hood.
2. Open brake bleeder screw on passenger side front caliper.
3. Let fluid bleed for 5 minutes.
4. Monitor brake fluid level while bleeding.
5. Close brake bleeder screw, when I see new fluid coming out.
6. Repeat process for driver side front caliper.
 
What fluid is specified? I suspect that any DOT3 fluid should suffice. I would urge you to include the rear brakes in your plan. It's worth it.
 
Originally Posted By: Chris142
might take more than 5 minutes for it to drain


Agreed, I've seen some that took more like a day... It's only going to drip at best...
 
Originally Posted By: TFB1
Originally Posted By: Chris142
might take more than 5 minutes for it to drain


Agreed, I've seen some that took more like a day... It's only going to drip at best...


Really? [censored]...
LOL

I might do the two person method then. What's the proper procedure for that?
Hold the pedal to the floor, and open the brake bleeder screw. Then close it after the fluid comes out, once the screw is closed, have the helper let go of the brake pedal. Correct?

Thanks for the help!
 
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Originally Posted By: Kestas
What fluid is specified? I suspect that any DOT3 fluid should suffice. I would urge you to include the rear brakes in your plan. It's worth it.


Yeah I believe it's DOT3. I will look it up.
I might do the rear brakes, but I'm not sure If I'll have time. I have to go help someone move so I'm hoping to fix the brakes before then.

Thanks!
 
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Two person method will be a true flush and take far less time than a gravity bleed.

Or take it to a shop and let them use a vacuum system to do it in about 20 minutes.
 
Originally Posted By: hypervish
1. Open brake fluid cap under hood.
2. Open brake bleeder screw on passenger side front caliper.
3. Let fluid bleed for 5 minutes.
4. Monitor brake fluid level while bleeding.
5. Close brake bleeder screw, when I see new fluid coming out.
6. Repeat process for driver side front caliper.


Some questions:

Does the brake fluid reservoir cap stay off the whole time? I was always leery of having it all run out in a hurry if I opened a bleeder if the reservoir cap was off.

Does the clear hose need to be submerged in a container of fluid?

I'm just going to swap a couple calipers; no need for a full flush since its all new fluid at this time.
 
If you use the tubing with its end submerged in brake fluid , then you can pump the brakes single handed. When I gravity bled the entire system on my Ranger in less than an hour. I left the top off, I checked the level and periodically topped it off. I used a qt of fluid to do the job.
 
"Some questions:

Does the brake fluid reservoir cap stay off the whole time? I was always leery of having it all run out in a hurry if I opened a bleeder if the reservoir cap was off.

Does the clear hose need to be submerged in a container of fluid?

I'm just going to swap a couple calipers; no need for a full flush since its all new fluid at this time."

No, you leave the reservoir cap on while pumping, otherwise the fluid will come out where the cap is. Top it off after you flush a little out from the bleeder screw.
The idea is to flush out all the old stuff first while replacing it with new stuff.

You want to work from the wheel farthest from the reservoir first. That being the passenger side rear, typically. As that brake line is the longest it will hold the most old fluid.

Since you are just swapping calipers that isn't necessary, but good to know.

The hose being submerged is to prevent air being sucked back into the brakes when you open and close the bleeder screws.
I have always done this with a small hose submerged.

You could try it without, but just be sure you test thoroughly before you drive, as a little air will compromise your braking ability significantly.
 
Originally Posted By: SuperDave456
"Some questions:

Does the brake fluid reservoir cap stay off the whole time? I was always leery of having it all run out in a hurry if I opened a bleeder if the reservoir cap was off.

No, you leave the reservoir cap on while pumping, otherwise the fluid will come out where the cap is.


I'll ask again. In a gravity bleed, should the reservoir cap stay on or off of the reservoir?
 
Originally Posted By: SuperDave456

No, you leave the reservoir cap on while pumping, otherwise the fluid will come out where the cap is.

I have never had a problem with fluid spilling out of the Master Cylinder reservoir while bleeding brakes with the cap off. Although it can happen when you compress the caliper pistons.
 
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Originally Posted By: SIXSPEED
Originally Posted By: SuperDave456

No, you leave the reservoir cap on while pumping, otherwise the fluid will come out where the cap is.

I have never had a problem with fluid spilling out of the Master Cylinder reservoir while bleeding brakes with the cap off. Although it can happen when you compress the caliper pistons.

x2 on this. cap off no matter what method. fluid will not (unless you have other issues) come out while pumping. only while pressing pistons back in a caliper..
 
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A word of warning if you are using the 'peddle pumping' method; do not push the peddle to the floor, only push as far as normal travel.

Particularly in an older car, you will swipe crud into the master seals and soon after be replacing/rebuilding the master cylinder.
 
I tried gravity bleeding on an older car. I got bored waiting for it to finish, walked away and forgot about it. When I returned the master cylinder reservoir was empty, and I had to start all over again.
 
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Use your PS turkey baster to drain and fill the cylinder prior to bleed, otherwise your pushing years old fluid through the system.
 
Originally Posted By: G.Frost
A word of warning if you are using the 'peddle pumping' method; do not push the peddle to the floor, only push as far as normal travel.

Particularly in an older car, you will swipe crud into the master seals and soon after be replacing/rebuilding the master cylinder.



That's probably the best piece of advice given in this thread...

Go get a Mityvac unit from Harbor Freight and pull it out the bleeder... Will also go much faster if suck the fluid out of the master cylinder before you start and refill with fresh, can use the Mighty-Vac unit for that as well... The Mityvac are plastic so brake fluid won't harm it if you get some inside it, don't use it with solvents, gasoline etc... They also have a brass looking off shore unit, but I have no experience with those...

http://www.harborfreight.com/mityvac-vacuum-pump-39522.html
 
Yea....the mityvac....or even my "MixMizer Pump" idea may work :P Likely better to just spread out pump outs every oil change, rather than pushing old fluid through the brake lines.....

Eventually all the fluid will be replenished....

I've started doing this with my power steering personally as well
wink.gif
Every oil change, I sipon about 8 oz. of fluid out of the reservoir, then add 8 ounces.....I don't notice any change in driveability, but I'd like to think it's adding some longevity to my ~24 year old P/S pump :P


And yes, I'm willing to bet your vehicle still specs the "DOT3" brake fluid.....go with whatever brand you are comfortable with....but I'd definitely check your cap(s) or the manual to be "safe" but I think the "DOT4" is the "latest spec" for new model vehicles...?
 
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